The proposed experiments focus on studies of patterns of stimulus evoked activity in somatosensory cortex (SI), and in particular, on the activation patterns evoked by repetitive skin stimulation. In the 01 year, animal experiments using the C14-2DG metabolic mapping method (2DG) and the infrared optical recording method for imaging intrinsic cortical signals (IR imaging) will be performed. The goal is to obtain and compare IR and 2DG images of the cortical response to the same stimulus conditions. In years 02-05, the IR optical recording technique will be employed to characterize the effects on stimulus evoked SI activity patterns of (i) NMDA receptor block, (ii) different frequencies of vibrotactile stimulation, and (iii) differing spatiotemporal patterns of skin stimulation. It is anticipated that the proposed studies will provide novel and useful information about the consequences of stimulus- evoked interactions among the multiple and spatially distributed neuronal populations activated by cutaneous stimuli. The information to be obtained should fill major gaps in what is currently known about the somatosensory cortical response to skin stimulation-gaps attributable principally to inadequacies of the methodologies which, at least to date, have been emphasized by experiments. In addition, the findings should provide direction to ongoing modeling and simulation studies of stimulus- directed somatosensory cortical network dynamics and the underlying neural mechanisms.